1. Field
Embodiments described herein generally relate to the gasification of hydrocarbons. More particularly, such embodiments relate to systems and methods for recovering heat from a syngas and generating steam therefrom.
2. Description of the Related Art
Gasification is a high-temperature process usually conducted at elevated pressure that converts carbon-containing material into mostly gaseous mixtures, including carbon dioxide, carbon monoxide, hydrogen, and methane. These gaseous mixtures are typically referred to as synthesis gas or, more succinctly, syngas. Upon production, syngas can be used as a feedstock to generate electricity and/or steam, a source of hydrogen, and for the production of other organic chemicals. Thus, gasification adds value to low-value feedstocks by converting them to marketable products. Coal, crude oil, coke, and high-sulfur residues have been used as gasification feedstock. The gasification feedstock is typically reacted in a gasifier (i.e. reactor) with an oxidizing medium in a reduced (stoichiometrically oxygen-starved) atmosphere at a high temperature and (usually) high pressure.
In certain gasification systems, the production of syngas provides particulate-containing fluids that are cooled, for example, by heat exchange with a heat transfer medium. Conditions of the particulate-containing fluids being cooled generally result in modest amounts of heat being recovered at relatively low temperatures. Generally, the heat is recovered for providing, for example, low pressure steam having a pressure ranging from about 1,379 kilopascals (kPa) to about 1,724 kPa. The heat recovered from particulate-containing fluids being cooled is generally considered to be of low quality within the gasification system and systems and methods to improve the use of such heat would be advantageous.
There is a need, therefore, for improved systems and methods for recovering heat from syngas and generating steam therefrom.